Selective signaling system



Nov. 20, 1928.

c. s. DEMAREsT SELECTIVE SIGNALING SYSTEM Filed May 25, 1923 IN VEN TOR C.v lemmf A TTORNEY Patented Nov. 20,' 1928. 'o A 1,691,962'

UNITED STATES PATsNT oil-l,='lcr..l

CHARLES S. DEMAREST, F NEW JERSEY, ASSIGNOB TO .AMERICAN TBLE- l EHONE AND TELEGRAPH COMPANY, A. CORPORATION 0F NEW YORK.

ysannc'rrvi: sIeNALING SYSTEM. application mea may a5, maa', 'semi No. 641,473.

This invention relates to selective signalthump, switchingv impulses and .voice curing systems, and more particularly to thev rents. The line L, in addition to being used application of such systems to railroad train for selective signaling, 1s also adaptedtohave 1 55 dispatching circuits. the usual phantom and composite circuits 5 One ofthe objects ofthe invention consists connected therewith. n

in the provision of circuits and apparatus for The details of this circuit may be now, sufincreasing the available transmission faciliflclentlyundelstoOd frOm a description of .its ties capable of beingobtained over a pair of OPGMIOQ. c lino Conductors, Assumlng a dispatcher at A wishes to com- Another object consists in utilizing altermlmloate Wlth One of the way stations connating current for signaling over 'the line nected withthe line L, theselector-keyKwill conductors, thus eliminating high lineV Voltbe Set OI @he 00de COIIbIDatOIl 0f theA parages previously required by the use of direct tlcular station desired, '1n a well-understood 65 oui-ront for this pui-poso, manner. For the-purpose of illustration2 it W These objects and further objects of the will be assumed that station B is the station invention will be apparent from the follow- Wanted. When key K is operated, it turns ing detailed description of the circuit and and its contact sprlng passes over the-unaoooinpanying drawing which illustrates masked teeth on the impulse Wheel, closing 70 one embodiment of the invention, contact 9 intermittently and completing a There is shown in the drawing a main or clrcuit from ground, conductor 10, winding dispatchers station A from which the line of pulslngor vl1ne relay 11 tobattery.. The: Conductors L extend to snbstations or way closure. of this circuit causes the energizationl stations, one of which is indicated at B. The 0f relay 11, which connects alternating cur- 'l5 dspatchers station A is provided with the rent through its upper and lower makeconordinary substation telephone set comprising tacts to the tip and ring conductors of the line a transmitter and a receiver by which con- L. Relay 8 is bridged across the-line L by versation may be carried onover conductors means of conductors 12, through repeating L with operators at the connected way sta, co1l13. When alternating current of suitable 80 tions which are provided with like instrufrequency is sent over the line L, relay 8 is v ments. A selector key K at the dispatchers energized and when thereed of this relay vistation A is of the well-known type and is brates it intermittently closes a circuit adapted to be adjusted to operate selector through its armature from ground, winding apparatus at any desired station. such seof relay 14 to battery. The intermittent clos- 85 lector apparatus being indicated at staing of this circuit causes the operation of retion B by the numeral 5. The selector lay 14. A condenser 22 i's bridged across reapparatus 5 which is Well-known in the lay14 to make it release slowly so that as long art, is shown as comprising a mechanias the reed of relay 8 is vibrating, relay 14 cal selector 6 operated by a relay 7 Assoremainsoperated. .When relay 14 operates, D0 ciated with each Way station is a relay corit completes a circuit through its front con- 40 responding to that illustrated by the refertact from battery, conductor 15, condenser 2 3,

ence numeral 8. This relay is of the vibratwindings of relay 7 to ground and charges ing make contact type and respondsreadily condenser 23. When relay 14 releases conto signaling impulses of short duration, such denser 23 discharges.v Relay 7 is operated by 95 as those which occur, for example, when the charge and discharge current of this conpulses of 1 35 cycle current are sent out on denser and causes the operation of selector 6 the line by the operation of relay 11 by the in a Well-known manner. The selector 6 is selector key K. The relay 8 is sensitive to stepped around by each signaling pulse until one frequency, for example 135 cycles, and it responds to its code combination,at whichxloo relatively insensitive to other frequencies, time a circuit is closed through the contacts and is therefore relatively free from the orof the selector from ground, winding 0frelay dinary sources of interference, such as those 16 to battery. Relay 16 is energized by the caused by mechanical vibration, Morse closure of this circuit and causes a suitable CAS 5 wishes to communicate With that station The operator at stationB upon noting. the illumination o' the signal 17 depresses kcy 18, thereby bridging thc. telephone -set 'l across the line conductors L. As the selector key K returned to normal at'ter sending the combination of ulses by which the selector 6 operated, the circuit by which relay 11 was energized is broken at contact 9 and said relay returns to normal. y The return of relay 11to normal disconnects alternating current from the line, whereupon relay 8 ceases operating and relays 14 and 7 release. The selector vvill at this time be restored to normal causing the lamp to be extinguished. The

dispatcher at station A who has inserted plug P in jack'J is enabled to carry on conversation With the Way station B by a talking circuit extending from station A over the tip and ring conductors of the line L, conductors 12 and repeating coil 13, conductors 19 to telephone set T at Way station B in a well understood manner.

, Composite sets equipped with the usual choke coils, condensers, etc. may be associated with the line conductors L as indicated at 20.

These sets terminate in Morse legs and telegraph transmission may be carried on over the conductors L in the customary manner.

At 21 there'is indicated in dotted lines the mannercin which the line conductors L may be connected to form one side of a phantom circuit.. The opposite side circuit may be similar to that illustrated and connected in like manner.

The circuit of this inventionthus permits simultaneous or independent dispatching and message transmission over the same pair of Wires for use in cases where one pair of Wires only isavailable or Where the tWo side circuits of the phantom group terminate at different points. It Will be apparent that the transmission of Morse signals does not affect the operation of the selectively operated devices at the Way stations. lVith thisarrangement a talking circuit provided With selective signaling may be obtained over the same pair of Wires as is used for telegraph transmission.

While this system has been described as having all signals originating at a master station, it is obvious that any of the Way stations may function as a sending` station by the addition ot apparatus similar to that indicated at said master station.

What is claimed is:

1. In a selectively controlled signal system comprising a central station and a plurality of Way stations, a line circuit connecting the central station and Way stations, phantom circuits and Morse circuits associated with the line circuit at the central station and Way stations, telephone sets at the central station and Way stations, a. source of alternating current at the central station, a source of direct current at the `Way stations, switching means including a selector key and a relay serially associated therewith for controlling the application of alternating current to the line circuit, said relay also controlling the connection over the line circuit between the telephone sets at the central station and Way stations, an alternating current relay at the Way stations responsive to the applicati-on of alternating current tothe line circuit, a direct current relay controlled by said alternating current relay, said direct current relay having a condenser bridged across its winding tomaintain it operated during the vibration of the armature of said alternating current relay, and selectively operated devices at the way stations actuated by the direct current relay, said selectively operated devices being unai'ected by the transmission of Morse signals over the line circuit.

2. In a railroad train dispatching system comprising a centralstation and a plurality of Way stations, a line circuit connecting the central station and Way` stations, phantom and Morse circuits associated With the line circuit, a source of alternating current at the central station, switching means including a selector key and a' relav serially connected therewith for controlling the application of alternating current to the line circuit, an alternating current relay bridged across the line circuit at the way stations mechanically and electrically tuned to be responsive to the application of ringing current, a direct current relay controlled by said alternating current relay having a condenser bridged across its winding of such capacity that said direct current relay is maintained energized during the operation of the alternating current relay, .and selectively operated devices at the Way stations actuated by the direct current relays, said selectively ioo operated devices being unresponsive to the transmission of Morse signals over the line circuit and connections of the telephone sets at the central station and way stations over such line circuit Y 3. In a railroad train dispatching systemy having a transmission line interconnecting *a4 central station and a plurality of `way stations, telephone sets, dispatching apparatus, phantom and Morse circuits connected with the line for independent and simultaneous transmission thereover between the central station and Way stations, a source of alternating current at the central station, a source of direct current at the way stations, switching means including a relay and a selector key for controlling the application of alternat-ing current to the transmission line, said relay also controlling the connection over the said vline between the telephone sets at 'the central station and way stations, an alternating current relay at the way stations responsive only to the application of alternating current to the transmission line, a direct current relay controlled by said alternating current relay, said direct current r'elay having a condenser bridged across its winding to maintain it operated during the' vibration of the armature of said alternating current relay, and selectively operated devices at the Way 10 stations actuated by the direct current relayg In testimony whereof, I have signed my name to thisv specification'thisth day of May,1923.

CHARLES s. DEMAREST. 

